The present invention relates generally to disengagable reduction gear units having bearings that are preloaded. Methods of use are also provided.
In the manufacture of disengagable reduction gearboxes, rotary bearings are utilized in the gearbox case to support input shafts and output shafts permitting rotation of the shafts. One particular type of bearing utilized in gearboxes is a thrust bearing, which is designed to support radial loads (thereby permitting rotation) and also high axial thrust loads. Thrust bearings may have a variety of configurations. One type of thrust bearing is a tapered roller bearing which consists of small tapered rollers disposed between a bearing cone and a bearing cup and arranged so that the axes of the rollers converge at a point on the axis of the bearing around which the cup and the cone are centered. One characteristic of thrust bearings is that they can be “pre-loaded” with an axial force when they are installed in an assembly. When a thrust bearing is pre-loaded, a certain amount of compressive force is applied to the cone as it seats in the cup of the bearing. The amount of pre-loading is determined by the particular use of the bearing. A significant pre-load generally makes the bearing harder to rotate, whereas minimal preloading leaves the bearing “loose.” Those skilled in the art with the benefit of this disclosure will appreciate that bearing pre-loading settings are often very precise and any variance or unintended change in the bearing pre-load that arises during the manufacturing process can hamper operation of the assembly in which they are utilized. Such variances or unintended changes in a pre-loaded bearing are often hard to prevent during the manufacturing process. This is particularly true of heavy equipment such as gearboxes where precision is often hard to maintain. Thus it would be desirable to provide a disengagable reduction gearbox in which thrust bearings utilized therein can be pre-loaded prior to assembly into the gearbox, and the desired pre-loaded can be maintained throughout the manufacturing process.
Likewise, in the manufacture of disengagable reduction gearboxes, the housing or case in which a shaft is supported must often be bored or otherwise machined to create a seat into which a movable bearing/shaft assembly is inserted. If the foregoing step is not performed with due care, o-ring seals between the bearing/shaft assembly and the gearbox housing are highly likely to leak oil or other lubricant contained within the gearbox. Moreover, such poor seals also enable the ingress of dirt or other debris into the gearbox case, thus potentially damaging the bearings, gears, or other internal components of the gearbox. Of course, those skilled in the art with the benefit of this disclosure will appreciate that the greater the precision used to machine such seats, the more expensive and time consuming the manufacturing process becomes. Thus, it would be desirable to provide a disengagable reduction gearbox with a sealing mechanism in which proper functioning is less dependent on the manufacturing process. It would also be desirable if such sealing mechanism not only inhibits leaks from within the gearbox, but also inhibits dirt or other debris from entering the interior of the gearbox.